package org.apache.lucene.search;

/**
 * Copyright 2004 The Apache Software Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.util.ArrayList;

/** Expert: Describes the score computation for document and query. */
public class Explanation implements java.io.Serializable {
    private float value; // the value of this node
    private String description; // what it represents
    private ArrayList details; // sub-explanations

    public Explanation() {
    }

    public Explanation(float value, String description) {
        this.value = value;
        this.description = description;
    }

    /** The value assigned to this explanation node. */
    public float getValue() {
        return value;
    }

    /** Sets the value assigned to this explanation node. */
    public void setValue(float value) {
        this.value = value;
    }

    /** A description of this explanation node. */
    public String getDescription() {
        return description;
    }

    /** Sets the description of this explanation node. */
    public void setDescription(String description) {
        this.description = description;
    }

    /** The sub-nodes of this explanation node. */
    public Explanation[] getDetails() {
        if (details == null)
            return null;
        return (Explanation[]) details.toArray(new Explanation[0]);
    }

    /** Adds a sub-node to this explanation node. */
    public void addDetail(Explanation detail) {
        if (details == null)
            details = new ArrayList();
        details.add(detail);
    }

    /** Render an explanation as text. */
    public String toString() {
        return toString(0);
    }

    private String toString(int depth) {
        StringBuffer buffer = new StringBuffer();
        for (int i = 0; i < depth; i++) {
            buffer.append("  ");
        }
        buffer.append(getValue());
        buffer.append(" = ");
        buffer.append(getDescription());
        buffer.append("\n");

        Explanation[] details = getDetails();
        if (details != null) {
            for (int i = 0; i < details.length; i++) {
                buffer.append(details[i].toString(depth + 1));
            }
        }

        return buffer.toString();
    }

    /** Render an explanation as HTML. */
    public String toHtml() {
        StringBuffer buffer = new StringBuffer();
        buffer.append("<ul>\n");

        buffer.append("<li>");
        buffer.append(getValue());
        buffer.append(" = ");
        buffer.append(getDescription());
        buffer.append("</li>\n");

        Explanation[] details = getDetails();
        if (details != null) {
            for (int i = 0; i < details.length; i++) {
                buffer.append(details[i].toHtml());
            }
        }

        buffer.append("</ul>\n");

        return buffer.toString();
    }
}
